In a bimetal-actuated temperature responsive valve assembly it is preferable to limit or decrease the hysteresis relative to the temperatures at which a bimetal disc is actuated to snap overcenter with the result that the degree of movement for the stroke of the bimetal disc is limited. It is also preferable to make the valve assembly as compact as possible by reducing the diameter of the bimetal disc with the result that the degree of movement or stroke of the disc will be decreased. As a result, such conventional bimetallic disc assemblies suffer the drawback that the degree of movement or stroke is insufficient to ensure a sufficient flow even when the valve means associated with the bimetal disc is in the fully opened position.